This will be the second time that SpaceX has tried to land a massive, 140-foot-tall Falcon 9 rocket on a platform floating offshore in the Atlantic ocean. The last time they tried to land a rocket on the drone ship, in January, the event did not go as well as planned.
That time, the rocket landed too hard, as you can see in this amazing vine that SpaceX released of the attempted rocket landing:
The rocket flies in at a 45-degree angle and then explodes on impact. What's incredible is that the rocket actually made contact with the barge in the first place, steering itself from 50 miles above Earth's surface.
The fins are located toward the top of the rocket as shown in the image below, which is Jon Ross's impression of what the landing would have looked like if successful.
Although the rocket was blown to bits, the drone ship suffered minor damage, shown below to be mostly intact with minimal burn marks.
Courtesy of Stephen Clark and Spaceflight Now
Spaceflight Now journalist Stephen Clark was there, at the Port of Jacksonville in Florida, and took this picture of the ship as it returned to shore.